Eluted DNA Difficult to Dissolve or Resuspend (HMW DNA Extraction (Monarch))

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Accepted Answer

DNA pellet or eluate shows poor solubility with visible aggregates or turbidity. DNA remains undissolved after standard elution protocol, requiring extended incubation. Common causes: 1) Binding time exceeded recommendation (> 4 min standard or > 8 min high input), causing excessive DNA compacting 2) Input amount exceeded limits: > 1 × 10⁷ cells at max agitation or > 5 × 10⁶ cells at low agitation or > 2 ml blood 3) Incomplete resuspension of cell pellet during nuclei preparation, resulting in clumped cells and tangled DNA 4) For blood: leukocyte pellets not completely resuspended (frozen or aged blood causes sticky leukocytes) 5) For blood: erythrocyte lysis extended too long, reducing leukocyte viability and causing stickiness Solutions: 1) Do not exceed binding time: 4 min in vertical rotating mixer (standard) or 8 min for high input samples 2) Reduce input to recommended amounts: ≤ 1 × 10⁷ cells (max agitation), ≤ 5 × 10⁶ cells (low agitation), ≤ 2 ml blood 3) Ensure complete resuspension during nuclei preparation: pipette thoroughly to break up cell clumps 4) For sticky leukocytes in frozen/aged blood: ensure complete resuspension after all pelleting steps 5) Proceed through erythrocyte lysis rapidly; do not extend RBC Lysis Buffer incubation time 6) For poorly dissolved DNA: incubate 5–15 min at 56°C with 300 rpm agitation, pipette with wide-bore tip, then leave overnight at room temperature or 30 min at 37°C